"I was exposed to a fire in my apartment and I come in as a burn victim," Vereen tells TV Guide.com. "I'm a wise, old guy who is the neighbor of a family he's adopted who has a terrible misfortune."

( Spoiler alert!) Vereen's character discovers that his surrogate family ran a drug laboratory at home when they all wind up in the hospital after an explosion. "He's crushed because he's a very lonely man," says the actor. "Mark and Izzie are taking care of him and Callie comes in, so I deal with those characters."

Asked whether he'll return to Seattle Grace, Vereen, who signed on for just one episode, jokes, "Maybe I'll burn myself again! I'll set myself on fire and they'll be like, 'Oh no, it's not you again! What do you keep burning yourself for?' But I want to be on the show. I like these guys!" - Reporting by Dana Meltzer Zepeda